Why the Ottomans Called Suleiman 'The Lawgiver'
In the West he is Suleiman the Magnificent, a name earned by the scale of his conquests and the splendour of his court. To his own subjects he was Kanuni, the Lawgiver. The two names describe the same sultan from opposite ends, and the Ottoman one points to the work that actually lasted.
The empire at its peak
Suleiman ruled from 1520 to 1566, the longest reign of any Ottoman sultan, and under him the empire reached the limit of its power. His armies took Belgrade and Rhodes early, crushed the kingdom of Hungary at the battle of Mohacs in 1526, and in 1529 stood at the walls of Vienna, the high-water mark of Ottoman expansion into Europe. His fleets, under the corsair admiral Barbarossa, contested the Mediterranean with the combined navies of Christian Europe. At his death the empire ran from Hungary to the Persian frontier and across North Africa toward the edge of Morocco.
Why they called him the Lawgiver
Conquest was expected of a sultan. What set Suleiman apart in Ottoman memory was the ordering of the state's secular law, the kanun. Religious law, the sharia, governed many areas of life, but it left gaps in matters of taxation, land tenure, criminal penalty and administration. Suleiman had these codified into a coherent body of regulation that applied across the whole sprawling empire, balanced against religious law rather than set against it. The aim was a system in which a subject in Hungary and a subject in Egypt could expect the same rules, and in which the sultan's own officials were bound by written law rather than by whim.
An age of stone and verse
His reign was also the cultural summit of the empire. The architect Mimar Sinan, who served Suleiman and his successors for half a century, built mosques whose domes still set the silhouette of Istanbul, the Suleymaniye chief among them. Poetry, miniature painting and the decorative arts reached a refinement that later Ottomans treated as a standard to be measured against. Suleiman himself wrote verse under a pen name, as several of the sultans did.
The cost at home
The glory had a private price that reads like the plot of a tragedy. Court intrigue, much of it tied to the rise of his wife Hurrem and the question of the succession, led Suleiman to order the execution of his able and popular eldest son Mustafa, and later of another son, decisions that haunted the dynasty afterwards. Magnificence abroad and order in the law did not buy peace inside the palace. He died on campaign in Hungary in 1566, an old man still in the field, and his officials are said to have hidden his death for days to keep the army steady until his successor could take control.
The Suleiman print belongs to the Riwayah Empires collection. You can see it here.
The vast mosque complexes Suleiman's reign raised were sustained by charitable endowment, not the treasury. For how that system worked, see what waqf was.